The invention concerns a disc brake, preferably a pneumatic disc brake, especially for a motor vehicle. The invention also concerns a brake caliper and a brake rotary lever.
In passenger cars and commercial vehicles, a disc brake is preferred. In the typical design of a disc brake, it consists of a brake caliper and internal mechanism, generally consisting of two brake pads and the brake disc. Forces are introduced to the internal mechanism, also called the brake application mechanism, via a force source, such as a pneumatically activated cylinder, by means of a piston rod. These forces are amplified by a cam mechanism and transferred as an application force via threaded tubes, also known as threaded pistons, threaded spindles, threaded rods, pressing dies, etc., by means of pressing pieces to the brake pads and brake disc. The wear on the brake disc and brake pads is balanced out by the threaded rods.
The application forces act across both brake pads on the brake disc, which experiences a slowdown in the rotational movement depending on the magnitude of the application force. The brake pad situated on the application face of the brake disc is called the application-side brake pad. The other brake pad is located on the other side of the brake disc, makes contact with a caliper back of the brake caliper, and is called the back-side brake pad. During a braking process, the application-side lining is moved toward the brake disc. Once this makes contact with the brake disc, the brake caliper is moved by the resulting counterforce with the back-side brake pad toward the brake disc. Now, if the back-side brake pad also makes contact with the brake disc, a braking action is generated.
Disc brakes are divided into axial brakes and radial brakes. These terms pertain to the introducing of the application force to a brake application mechanism in relation to the brake disc. Thus, with the axial brake, the application force is introduced axially to the brake disc, i.e., in the direction of the brake disc axis. With the radial brake, the application force is introduced to a brake application mechanism in the radial direction of the brake disc.
Conventional radial brakes have at least two housings or brake caliper components. This is seen as a drawback in regard to the number of parts and the required sealing surfaces.
In the course of weight reduction and costs in the automotive industry, especially in the commercial vehicle sector, there is a constant demand for cost- and weight-optimized disc brakes as far as possible with the same or even better performance and low number of parts.
Therefore, the problem which the present invention proposes to solve is to create an improved disc brake.
Another problem is to provide an improved brake caliper.
Yet another problem is to create an improved brake rotary lever.
The problem is solved by a disc brake with the features of the present invention.
The additional problem is solved by a brake caliper with the features of the present invention.
The further problem is solved by a brake rotary lever with the features of the present invention.
A disc brake is created in which the number of parts is less than in the prior art, while at the same time an improved force introduction into the structure of the brake caliper exists. Furthermore, a reduction of the sealing surfaces is made possible.
A disc brake according to the invention, preferably one actuated by compressed air (pneumatically), especially for a motor vehicle, includes a brake application mechanism with a brake rotary lever, at least one spindle unit, each spindle unit having a threaded rod that screws into a bridge, and a brake caliper, especially a sliding caliper, which preferably covers an edge region of a brake disc in the manner of a frame. The brake caliper has a brake application portion and a caliper back, which are connected together by tie bars. The brake application mechanism with the brake rotary lever is received on an application face of the brake disc in the brake application portion of the brake caliper. The brake application portion of the brake caliper has the following features: a first region in which the brake application mechanism and a force transmission portion of the brake rotary lever are arranged, a second region which is formed as a lever housing and receives a lever portion of the brake rotary lever, wherein between the first region and the second region there is arranged a support wall with a bearing portion, forming a pivot bearing with a brake rotary lever axis, that runs parallel to the brake disc, for the brake rotary lever.
Owing to this design of the brake caliper, it is possible to reduce the space required for the disc brake, so that a much greater clearance to an axle of an associated motor vehicle is made possible.
In one embodiment, two or more spindle units are provided, each of them having a threaded rod screwed into the bridge. This results in a large area of usage.
The construction of the brake application portion is such that the division into two regions results in an especially space-saving construction in terms of the height of the brake application portion of the brake caliper. Thus, the first region of the brake application portion has at least one bottom wall which runs substantially parallel with a portion of a top wall of the brake application portion.
Furthermore, this compact construction achieves a reduction of the sealing surfaces, since a one-piece embodiment of the brake caliper is possible.
The first region is separated at least partly from the second region by the support wall. Especially advantageously here, the support wall is arranged parallel to the brake disc and so as to be connected to the at least one bottom wall. It can therefore form the pivot bearing for the brake rotary lever, which can at the same time be easily installed by simple inserting through the first region, even though it requires a relatively long length. The inserting is made possible by the fact that a passageway between the first region and the second region of the brake application portion is provided between the bearing portion of the support wall and the inside of the top wall.
The second region of the brake application portion also has a bottom wall, which runs substantially parallel to a further portion of the top wall of the brake application portion. This results in the aforementioned space-saving design.
It is furthermore advantageous for the additional portion of the top wall of the brake application portion to have a flange, in the second region in the end region of the lever housing, with an opening for the attachment of a power drive for the disc brake. In this way, no additional component is needed for the attachment of a force generating element, such as a compressed air cylinder. The flange can be produced by machining, for example, and can also be adapted to different dimensions for its mounting or installation.
In another embodiment, it is provided that the bottom wall of the lever housing has, on its inside, an end stop portion with an end stop surface projecting toward the interior of the lever housing. The end stop surface is arranged beneath the opening of the flange. This end stop surface interacts with an end stop surface of the brake rotary lever, especially with its lever portion received in the lever housing as a stroke-limiting element. By appropriate machining of these two interacting end stop surfaces, a brake caliper can be used for at least two different brakes.
Furthermore, it is provided that the second region of the brake application portion of the brake caliper has a rear wall, which is arranged parallel to the support wall. In this way, on the one hand installation space is saved and, on the other hand, a stable lever housing is formed.
The bottom walls arranged parallel with the top wall as well as the support wall and rear wall arranged parallel to each other and perpendicular to the former allow the brake caliper to be formed as a casting with only one core or with two mirror-image cores.
In an especially advantageous manner, the support wall is connected to a slanted support wall, the slanted support wall extending away from the brake disc at an inclination in the direction of a brake disc axis and being connected to the bottom wall of the second region. With side walls, a so-called outer pocket is formed, by way of which a weight and casting optimization can be achieved.
A further advantage is created if the slanted support wall forms an angle with the bottom wall whose value is not equal to 0°. The angle can have a value, for example, in the range of 15° to 45°, preferably 30°. This makes possible an effective force introduction to the brake caliper during braking processes.
A further advantageously stable and weight-optimized embodiment is achieved in that a cross section of the lever housing tapers in the longitudinal direction toward the brake disc starting at the connection of the slanted support wall to the bottom wall and as far as the support wall or the passageway.
For a compact construction with the same or better performance at the same time, as well as easy installation, it is provided that the brake rotary lever has a curved, slender shape in its longitudinal direction with a lever body having side portions, a longitudinal stiffening, and at least one thrust bearing portion.
An especially stable and compact embodiment is achieved in that the lever body of the brake rotary lever has a lever portion and a force transmission portion, which are connected at the bottom side of the lever body to the longitudinal stiffening.
In another embodiment, the lever portion has a driving end, which at a top side a driving portion for interaction with a piston rod of a force generating element is defined, and the driving end having an end stop surface at the bottom side, which bottom side lies opposite the driving portion. The machining of the end stop surface has already been pointed out above, including the benefits in interaction with the end stop surface on the bottom wall of the lever housing.
Furthermore, it is provided that the force transmission portion of the lever body has a roughly semicircular middle web, on either side of which is arranged a semicircular thrust bearing portion with a respective thrust bearing surface. The middle web protrudes from the thrust bearing portions. In this way, relative movements of the brake rotary lever can be advantageously reduced if the middle web protruding from the thrust bearing portions is received in a guide of the bridge, thus forming a form-fitted lever guidance of the brake rotary lever in the direction of the brake rotary lever axis.
In yet another embodiment, on the side opposite the thrust bearing surfaces of the thrust bearing portions there is formed a bearing seat with a roughly semicircular cross section. The bearing seat has a center line which is identical to the brake rotary lever axis. With this bearing arrangement, a stable hysteresis can be made possible over the entire service life.
For a required eccentricity of the force transmission portion of the brake rotary lever, the center line of the bearing seat is arranged off center from a midpoint of the radii of the semicircular thrust bearing surfaces of the thrust bearing portions.
Furthermore, it is provided that a radius of the bearing seat is smaller than a radius of the thrust bearing surfaces of the thrust bearing portions, for example around 0.6 to 0.4 times smaller. This yields the advantage that, together with the curved, most slender possible shape of the brake rotary lever, an easy installation of the brake rotary lever is made possible.
It is especially advantageous to design the brake caliper as a single piece. Among other things, this reduces the sealing surfaces and the number of parts. It is also advantageous if at least the brake application portion of the caliper containing the brake application mechanism, including the rotary lever, is in one-piece.
In one embodiment, the disc brake can have an adjustment device.
The disc brake is designed as a radial brake.
A brake caliper according to the invention is provided for the above-described disc brake.
A brake rotary lever according to the invention is provided for the above-described disc brake.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.
Coordinates x, y, z in the figures serve to help with orientation.
The reference sign ZS indicates an application face of the disc brake 1, and reference sign RS indicates a back (reaction-side) face of the disc brake 1.